Acrylic-based adhesives are well-known in applications requiring fast curing at ambient or room temperatures and the adhesive compound being tough and flexible after cure. See, for example, U.S. Pat. Nos. 4,536,546, 5,656,345, 6,602,958, 7,479,528, 5,112,691, and 7,776,963. These acrylic-based adhesives are sometimes in the form of a two part system that is stored separately prior to use and then mixed at the time of use. These two part acrylic-based adhesives, however, have limitations and performance problems. Storage stability is often a concern. Low impact strength is another weakness of these adhesives. Heat and moisture resistance at elevated temperatures is another property sometimes lacking. With increased scrutiny of chemical contaminants entering water supplies in potable water applications, avoidance of migration of unreacted components or ingredients is strongly desired. These limitations and performance properties can be significant issues when trying to bond thermoplastic pipe and fittings made of, for example, polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC) and/or poly(acrylonitrile-butadiene-styrene) (ABS) materials.
Thus there is a need for an improved two part reactive acrylic-based adhesive system or composition having desirable storage stability, impact strength, heat and moisture resistance properties, and having low concentrations of unreacted components to avoid migration of chemical contaminants into the potable water systems.